lb-gen-release-notes should find out dependencies

When possible lb-gen-release-notes should walk the project dependencies and automatically create a string like

This version uses Phys v30r6, Rec v30r6, Lbcom v30r6, LHCb v50r6, Gaudi v32r2 and LCG_96b with ROOT 6.18.04.

In addition having this auto generated would be nice:

This version is released on branch [master](../tree/master). The previous release on that branch  was [v30r1](../tags/v30r1).

which would render like

This version is released on branch master. The previous release on that branch was v30r1.